The invention generally relates to insulation layers on semiconductor substrates, along with methods of forming the same, and microelectronic devices that include the insulation layers.
There is an increasing interest in forming advanced complementary metal-oxide semiconductor (CMOS) devices. In is generally believed that such devices may require high dielectric constant (high-k) gate insulators to maintain sufficient capacitance while minimizing tunneling. Physical vapor deposition (PVD) and chemical vapor deposition (CVD) of high-k materials often results in lower-k interface layers that are believed to result from unwanted reactions with the silicon substrate. See e.g., K. A. Son et al., J. Vac. Sci. Technol. A 16, 1670-1675 (1998), B. H Lee et al., Appl. Phys. Lett. 76, 1926 (2000), G. B. Alers et al., Appl. Phys. Lett. 73, 1517-1519 (1998), S. K. Kang et al., Thin Sol. Films 353, 8-11 (1999), and T. M. Klein et al., Appl. Phys. Lett. 75, 4001-4003 (1999). These reactions are believed to result from the non-equilibrium nature of the deposition. High-k CVD from metal-organic sources on clean silicon (Si) typically involves the breaking of a metal-ligand bond, chemisorption of the metal complex, forming, for example, metal-silicon, silicon-carbon, silicon-hydroxide bonds, and the like, and subsequent oxidation.
Notwithstanding these previous efforts, there remains a need in the art for metal silicate insulators that have high dielectric constants which may be employed in advanced electronic devices without markedly increasing current leakage or tunneling through a corresponding gate stack.
In one aspect, the invention provides a method of forming an insulation layer on a semiconductor substrate. The method comprises modifying a surface of a semiconductor substrate with a metal or a metal-containing compound and oxygen to form an insulation layer on the surface of the semiconductor substrate, wherein the insulation layer comprises the metal or metal-containing compound, oxygen, and silicon such that the dielectric constant of the insulation layer is greater relative to an insulation layer formed of silicon dioxide, and wherein the insulation layer comprises metal-oxygen-silicon bonds.
In another aspect, the invention provides a surface-modified semiconductor substrate comprising a semiconductor substrate comprising silicon; and an insulation layer formed on a surface of the semiconductor substrate. The insulation layer comprises a metal or metal-containing compound, oxygen, and silicon such that the dielectric constant of the insulation layer is greater relative to an insulation layer formed of silicon dioxide, and the insulation layer also comprises metal-oxygen-silicon bonds.
In another aspect, the invention provides a microelectronic device comprising the surface-modified semiconductor substrate described above.
These and other aspects and advantages of the present invention are set forth in greater detail herein.